The Earth’s most elaborate ground-based telescope, the , celebrated going from limited use to full-scale production as its 50th came online this month. The milestone marked thirty years of planning and over a decade of construction, and already bears witness to some pretty amazing results.
ALMA – the acronym means ‘soul’ in Spanish – may not be imbued with a ‘soul,’ but is backed by a very big brain. The array’s correlator, a custom-built supercomputer designed to withstand the rigors of its high-altitude site in the Andes Mountains of Chile, has 134 million processors. Each processor is dedicated to continuously analyzing and combining signals collected by the antennas, essentially allowing them to function as a single giant telescope.
Changing the observing area of the antennas is no small feat; each dish must move with exact precision, in time with the others. Giant transporter trucks can also move the dishes for additional perspective. Maximizing the total observing area by employing the greatest distance between dishes – 16 kilometers – makes an angular resolution equivalent to that of the Hubble Space Telescope possible.
Recent research published in the journal Nature confirms ALMA’s power. In combination with the South Pole Telescope’s wide area, millimeter wave surveys, ALMA’s spectroscopic power is providing new insights into unusual and far-infrared luminous galaxies, which shine due to absorption of visible and ultraviolet light from stars and active galactic nuclei.
ALMA is able to capture light with wavelengths around 3 millimeters. Over billions of years, the expansion of the universe stretches wavelengths. By measuring the stretch, scientists can calculate the length of the light’s journey and place each galaxy at the correct point in cosmic history. ALMA is now able to measure a galaxy in just a few minutes – compared to previous measurements, which may have taken many nights. ALMA’s confirmed ability to quickly measure the motion of an internal gas in a number of distant galaxies is unprecedented, and speaks of the discoveries to come.
ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences of Japan (NINS) in cooperation with the Academia Sinica (AS) in Taiwan.
- Amber Harmon